The first few verses of chapter one constitute an introduction to the book of Acts, giving us the key to the book; we are all witnesses of Christ.  Here we have revealed the essential strategy by which Jesus Christ proposes to change the world, a strategy which is the secret of the revolutionary character of the church when it is operating as it was intended to operate. I strongly suspect that most Christians suffer from a terrible inferiority complex when we confront the world around us. We have bought the idea of many that the church is quite irrelevant, a not-at-all-important segment of society. That view is absolutely false. The church is the most important body in the world today — far and away beyond every other body — because whatever happens in the world happens as a result of something that is, or is not, happening in the church.